Temperature control method and apparatus, and plasma processing apparatus

Abstract

A temperature control method and apparatus, and a plasma processing apparatus are provided. The temperature control method includes the steps of, during an idle state in which a substrate processing is not performed, controlling a temperature of a heat transfer medium in a circulation channel by a second heat exchanger and a heater to control a temperature of an electrode to be maintained at a predetermined set temperature, and when a high frequency power is applied to the electrode to start the substrate processing, reducing the temperature of the heat transfer medium below the set temperature of the electrode through the use of a first heat exchanger and the second heat exchanger to maintain the temperature of the electrode at the set temperature.

1 . A temperature control method of an electrode, to which a high frequency power for generating a plasma in a plasma processing apparatus is applied, wherein the temperature control method is carried out by using a temperature control apparatus including: 
 a circulation channel for circulating a heat transfer medium through an inside of the electrode and provided with;    a first heat exchanger for performing a heat exchange of the heat transfer medium passed through the electrode by a sensible heat of a liquid coolant;    a second heat exchanger for performing a heat exchange of the heat transfer medium passed through the first heat exchanger by a latent heat of a coolant; and    a heater for heating the heat transfer medium supplied to the inside of the electrode,    the temperature control method comprising the steps of:    during an idle state in which a substrate processing is not performed, controlling a temperature of the heat transfer medium in the circulation channel by the second heat exchanger and the heater to control a temperature of the electrode to be maintained at a predetermined set temperature; and    when the high frequency power is applied to the electrode to start the substrate processing, reducing the temperature of the heat transfer medium below the set temperature of the electrode through the use of the first heat exchanger and the second heat exchanger to maintain the temperature of the electrode at the set temperature.    
   
   
       2 . The temperature control method of  claim 1 , wherein the electrode for generating the plasma is an upper electrode, and 
 the plasma processing apparatus includes a lower electrode for mounting a substrate thereon, another high frequency power being applicable to the lower electrode, and    a temperature difference ΔT between the set temperature of the upper electrode during the idle state and a target temperature of the heat transfer medium during the substrate processing is set as:        ΔT=k ( aA+bB )× D/C,      wherein k is a conversion factor from an electric power to a temperature; A is the high frequency power applied to the upper electrode; B is the high frequency power applied to the lower electrode; a is a factor showing a ratio of an influence of the high frequency power applied to the upper electrode, to an influence of all the high frequency powers, on the temperature of the upper electrode; b is a factor showing a ratio of an influence of the high frequency power applied to the lower electrode, to the influence of all the high frequency powers, on the temperature of the upper electrode; C is a processing time per substrate; and D is a high frequency power application time during the processing time C.    
   
   
       3 . The temperature control method of  claim 1 , wherein the circulation channel is provided with a bypass passage for circulating the heat transfer medium so that the heat transfer medium bypasses the electrode for generating the plasma, and further comprising the steps of: 
 when the substrate processing is ended, increasing the temperature of the heat transfer medium by using the heater by circulating the heat transfer medium through the bypass passage;    circulating the heat transfer medium so that the heat transfer medium passes through the inside of the electrode to stabilize the temperature of the heat transfer medium at the set temperature.    
   
   
       4 . The temperature control method of  claim 3 , wherein the temperature of the heat transfer medium is stabilized at the set temperature by alternately performing a circulation of the heat transfer medium passing through the bypass passage, and a circulation of the heat transfer medium passing through the inside of the electrode.  
   
   
       5 . The temperature control method of  claim 1 , wherein the liquid coolant is water.  
   
   
       6 . A temperature control apparatus of an electrode, to which a high frequency power for generating a plasma in a plasma processing apparatus is applied, comprising: 
 a circulation channel for circulating a heat transfer medium through an inside of the electrode and provided with;    a first heat exchanger for performing a heat exchange of the heat transfer medium passed through the electrode by a sensible heat of a liquid coolant;    a second heat exchanger for performing a heat exchange of the heat transfer medium passed through the first heat exchanger by a latent heat of a coolant;    a heater for heating the heat transfer medium supplied to the inside of the electrode; and    a control unit, during an idle state in which a substrate processing is not performed, for controlling a temperature of the heat transfer medium in the circulation channel by the second heat exchanger and the heater to control a temperature of the electrode to be maintained at a predetermined set temperature, and when the high frequency power is applied to the electrode to start the substrate processing, for reducing the temperature of the heat transfer medium below the set temperature of the electrode through the use of the first heat exchanger and the second heat exchanger to maintain the temperature of the electrode at the set temperature.    
   
   
       7 . The temperature control apparatus of  claim 6 , wherein the electrode for generating the plasma is an upper electrode, and 
 the plasma processing apparatus includes a lower electrode for mounting a substrate thereon, another high frequency power being applicable to the lower electrode, and    the control unit calculates to set a temperature difference ΔT between the set temperature of the upper electrode during the idle state and a target temperature of the heat transfer medium during the substrate processing as:        ΔT=k ( aA+bB )× D/C,      wherein k is a conversion factor from an electric power to a temperature; A is the high frequency power applied to the upper electrode; B is the high frequency power applied to the lower electrode; a is a factor showing a ratio of an influence of the high frequency power applied to the upper electrode, to an influence of all the high frequency powers, on the temperature of the upper electrode; b is a factor showing a ratio of an influence of the high frequency power applied to the lower electrode, to the influence of all the high frequency powers, on the temperature of the upper electrode; C is a processing time per substrate; and D is a high frequency power application time during the processing time C.    
   
   
       8 . The temperature control apparatus of  claim 6 , wherein the circulation channel is provided with a bypass passage for circulating the heat transfer medium so that the heat transfer medium bypasses the electrode for generating the plasma, and 
 the control unit, when the substrate processing is ended, increases the temperature of the heat transfer medium by using the heater by circulating the heat transfer medium through the bypass passage, and further,    circulates the heat transfer medium so that the heat transfer medium passes through the inside of the electrode to stabilize the temperature of the heat transfer medium at the set temperature.    
   
   
       9 . The temperature control apparatus of  claim 8 , wherein the control unit alternately performs a circulation of the heat transfer medium passing through the bypass passage, and a circulation of the heat transfer medium passing through the inside of the electrode to stabilize the temperature of the heat transfer medium at the set temperature.  
   
   
       10 . The temperature control apparatus of  claim 6 , wherein the liquid coolant is water.  
   
   
       11 . A plasma processing apparatus comprising: 
 an electrode, to which a high frequency power for generating a plasma is applied;    a circulation channel for circulating a heat transfer medium through an inside of the electrode and provided with;    a first heat exchanger for performing a heat exchange of the heat transfer medium passed through the electrode by a sensible heat of a liquid coolant;    a second heat exchanger for performing a heat exchange of the heat transfer medium passed through the first heat exchanger by a latent heat of a coolant;    a heater for heating the heat transfer medium supplied to the inside of the electrode; and    a control unit, during an idle state in which a substrate processing is not performed, for controlling a temperature of the heat transfer medium in the circulation channel by the second heat exchanger and the heater to control a temperature of the electrode to be maintained at a predetermined set temperature, and when the high frequency power is applied to the electrode to start the substrate processing, for reducing the temperature of the heat transfer medium below the set temperature of the electrode through the use of the first heat exchanger and the second heat exchanger to maintain the temperature of the electrode at the set temperature.    
   
   
       12 . The plasma processing apparatus of  claim 11 , wherein the electrode for generating the plasma is an upper electrode, and 
 the plasma processing apparatus further comprises a lower electrode for mounting a substrate thereon, another high frequency power being applicable to the lower electrode, and    the control unit calculates to set a temperature difference ΔT between the set temperature of the upper electrode during the idle state and a target temperature of the heat transfer medium during the substrate processing as:        ΔT=k ( aA+bB )× D/C,      wherein k is a conversion factor from an electric power to a temperature; A is the high frequency power applied to the upper electrode; B is the high frequency power applied to the lower electrode; a is a factor showing a ratio of an influence of the high frequency power applied to the upper electrode, to an influence of all the high frequency powers, on the temperature of the upper electrode; b is a factor showing a ratio of an influence of the high frequency power applied to the lower electrode, to the influence of all the high frequency powers, on the temperature of the upper electrode; C is a processing time per substrate; and D is a high frequency power application time during the processing time C.    
   
   
       13 . The plasma processing apparatus of  claim 11 , wherein the circulation channel is provided with a bypass passage for circulating the heat transfer medium so that the heat transfer medium bypasses the electrode for generating the plasma, and 
 the control unit, when the substrate processing is ended, increases the temperature of the heat transfer medium by using the heater by circulating the heat transfer medium through the bypass passage, and further,    circulates the heat transfer medium so that the heat transfer medium passes through the inside of the electrode to stabilize the temperature of the heat transfer medium at the set temperature.    
   
   
       14 . The temperature control apparatus of  claim 13 , wherein the control unit alternately performs a circulation of the heat transfer medium passing through the bypass passage, and a circulation of the heat transfer medium passing through the inside of the electrode to stabilize the temperature of the heat transfer medium at the set temperature.  
   
   
       15 . The temperature control apparatus of  claim 11 , wherein the liquid coolant is water.